This invention relates to conveyor lubricants and to a method for conveying articles. The invention also relates to conveyor systems and containers wholly or partially coated with such lubricant compositions.
In commercial container filling or packaging operations, the containers typically are moved by a conveying system at high rates of speed. Copious amounts of aqueous dilute lubricant solutions (typically based on fatty acids, amines or surfactants) are typically applied to the conveyor or containers using spray or pumping equipment. These lubricant solutions permit high-speed operation of the conveyor and limit marring of the containers or labels, but also have some disadvantages. For example, aqueous conveyor lubricants based on fatty amines typically contain ingredients that can react with spilled carbonated beverages or other food or liquid components to form solid deposits. Formation of such deposits on a conveyor can change the lubricity of the conveyor and require shutdown to permit cleanup. Some aqueous conveyor lubricants are incompatible with thermoplastic beverage containers made of polyethylene terephthalate and other plastics, and can cause stress cracks to form in the base of the container. Dilute aqueous lubricants typically require use of large amounts of water on the conveying line, which must then be disposed of or recycled.
The present invention provides, in one aspect, a method for lubricating the passage of a container along a conveyor comprising applying to at least a portion of the container-contacting surface of the conveyor or to at least a portion of the conveyor-contacting surface of the container a coating comprising a hydrophilic material wherein the lubricating properties of the coating are enhanced by contact with a polar liquid; polymerizing or otherwise solidifying the coating; and contacting the coating with such polar liquid.
The present invention provides, in another aspect, a lubricated conveyor or container, having a polymeric coating on a container-contacting surface of the conveyor or on a conveyor-contacting surface of the container, wherein the coating comprises a hydrophilic material and the lubricating properties of the coating are enhanced by contact with a polar liquid.